High lithium storage performance of Ni0.5Fe0.5O1−xNx thin film with NiO-type crystal structure

The large voltage hysteresis of the NiO anode, which owes much to the intermediate product Li₂NiO₂, is one of the main obstacles to its practical application in lithium-ion batteries. In this work, we show that the incorporation of Fe- and N-ions in the NiO lattice can suppress the formation of intermediate product Li₂NiO₂ and thus greatly reduces the voltage hysteresis of the NiO anode from ∼1.2 to ∼0.9 V. In comparison with the pure NiO electrode, the Ni_0.5Fe_0.5O_1−xN_x anode exhibits significantly enhanced reversible specific capacity (959 mAh·g⁻¹ at 0.3 A·g⁻¹), cycling stability (capacity retention of 96.1% at 100th cycle relative to the second cycle) and rate capability (442 at 10 A·g⁻¹). These results provide a practical method to enhance the lithium storage performance of the NiO anode and more importantly a new solution to the large voltage hysteresis of conversion-type anodes.